Think like a Bayesian (without all the math)

Bayesian thinking is the most powerful mental model modern scientists and rationalists use to improve their reasoning and decision-making skills, make good predictions, and arrive at true beliefs.

Bayes formula tells you how you should change your beliefs in response to the evidence you observe.

In this post, I will share with you the two most useful practical implications of this way of thinking, which you can start using in real-life situations right away (without going into all the complicated math).

Think probabilistically

The biggest lesson from Bayesian thinking is that your beliefs should be grayscale rather than black and white.

Start assigning a level of confidence to your beliefs, and express it as a probability between 0% and 100%.

Absolute certainty is not mathematically possible, and will inevitably lead to mistakes. What's worse - it makes it painful for people to let go of their cherished beliefs, and reluctant to change their minds.

Using probabilities is the key to becoming more open-minded, and it will help you build a much more flexible and nuanced worldview.

Incrementally update your beliefs

Most people are terrible at changing their mind. They stick to what they know until some overwhelming evidence forces them to change their beliefs. This approach is very blunt and inefficient - it makes them blind to subtle clues that could've made their map of the world more accurate.

It's much better to:

Change your beliefs a little bit at a time, in response to all evidence (no matter how small).

Update your confidence level every time you learn something new, shift the probabilities up or down. The more surprising and unexpected the new evidence is, the more you should change your beliefs (because it means that your existing beliefs have led you to make a very inaccurate prediction).

Realize that having static and unchanging confidence in your beliefs is holding you back from learning new things, becoming smarter, and getting a more accurate picture of the world.

Not every change is an improvement, but every improvement is necessarily a change. You can't do anything better unless you can manage to do it differently.

For a normal person, changing their mind about something they care about is often a traumatic and life-changing event - so they avoid it. But if you're a rationalist, you change your mind all the time.

Your confidence can go from 95% to 70% to 80% to 60% to 45%, updating every time you learn something new - so it is never scary to face the new evidence, you are not afraid or reluctant to learn things that might disagree with your beliefs, and changing your mind becomes as easy as updating your confidence from 55% to 45%.

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